Epstein Barr Virus (EBV), a human herpes virus, causes infectious mononucleosis in normal adolescents and is carried by a majority of the human population as a persistent asymptomatic infection characterized by viral shedding from lytically infected cells and latently infected circulating B cells. EBV is also associated with B lymphoproliferative diseases and epithelial cell malignancies including African Burkitt's lymphoma, Hodgkin's Disease, and nasopharyngeal carcinoma. Normal B lymphocytes infected in vivo or in vitro can proliferate indefinitely giving rise to lymphoblastoid cell lines (LCL) which contain the entire EBV genome in an episomal latent state. The latent state involves expression of latency associated gene products-six nuclear proteins (EBNAs), two small RNAs (EBERs), and two integral membrane proteins (LMP1 and LMP2). These mediate latent infection and/or growth transformation. LMP2 is simultaneously transcribed by two promoters to yield two nearly identical mRNAs which differ only in their first exon- LMP2A and LMP2B. LMP2A has been shown to function as a negative regulator of the Src family Lyn protein tyrosine kinase (PTK) and the Syk PTK which is important for maintaining viral latency by preventing normal B cell signal transduction. LMP2B may regulate LMP2A function by modulating the spacing between individual LMP2A amino-terminal domains in LMP2A aggregates in the plasma membrane of EBV plus LMP2A plus LCLs. LMP2A contains 8 tyrosine residues in its amino-terminal domain which are phosphorylated in EBV latently infected cells. These phosphotyrosines may bind to SH2 domains in proteins important for signal transduction thereby regulating viral latency. My research consists of generating more LCLs containing site specific mutations in the tyrosines located in the amino-terminal domain to determine the amino acids critical for LMP2A interaction with PTKs and other SH2 domain containing proteins. The functional significance of these mutations will be investigated by analyzing B cell signal transduction through calcium mobilization, activation of EBV lytic replication, and tyrosine phosphorylation.